With the recognition that automobiles are a major contributor to air pollution, automobile manufacturers of performance cars and otherwise have come to rely on computers as a means of controlling engine operating parameters while maximizing efficiency. Computers have been relied upon because of their almost infinite ability to adapt to a changing engine operating environment while optimizing engine operating parameters.
For example, it has long been known that a cold automobile engine requires a richer air-fuel mixture than a warm engine for proper operation. Even after an engine has reached a normal operating temperature, the air-fuel mixture must be constantly adjusted to changing load conditions. An idling engine, for example, need only be supplied with enough fuel to maintain an idle speed at a constant number of revolutions per minute (RPM), whereas an engine under load requires a much richer fuel mixture.
To improve combustion efficiency, fuel injection has been increasingly relied upon as a means of achieving an optimal air-fuel mixture across the full range of engine speeds and loads. In fuel injection systems, a precise volume of fuel is sprayed either directly into the combustion chamber or into the air stream during an intake period of each combustion cycle. Fuel may be introduced by an injector located near an intake of each cylinder (direct injection) using a number of injectors or a single injector may be located proximate an engine throttle (throttle body injection). In both cases the volume of fuel introduced during an injection cycle is usually controlled by fuel injection control module based upon a throttle position.
Under direct injection or throttle body injection, the timing of the fuel injection is critical to good air-fuel mixing. If the timing of the injection is early or late the sprayed fuel simply condenses on the bottom of the intake manifold. The condensed fuel then enters the cylinders during subsequent intake cycles as a liquid instead of a vapor resulting in poor and incomplete combustion.
Another factor in ensuring complete combustion of the air-fuel mixture in the combustion chamber is the proper timing of a combustion spark. In the past, proper timing of the spark was controlled through a coil firing and spark distributing circuit (distributor) mechanically coupled to the engine camshaft. As a cylinder entered a combustion stroke, the mechanical movement of the camshaft positioned a rotor within the distributor towards a contact of a high voltage wire to the spark plug. At a pre-determined number of degrees before a piston within the combustion cylinder reached its upper-most position (top dead center (TDC)), an ignition control module associated with the distributor senses the position of distributor rotor shaft and applies a voltage pulse to an ignition coil firing the spark plug through the rotor and distributor.
Other ignition systems of more recent design (distributorless ignition systems) may provide an ignition coil for each pair of combustion cylinders while others provide a coil for each cylinder. A separate ignition module firing circuit is provided for each ignition coil. Such ignition systems do not have a distributor coupled to the camshaft for triggering a combustion spark through the coil and instead rely on solid state sensors (e.g., Hall effect sensors, magnetic pick-up coils, etc.) that are typically placed proximate the camshaft and crankshaft for detecting engine position. Such systems typically have a number of actuator structures (e.g., slots, cogs, pins, etc.) attached to the camshaft and crankshaft for activating the sensors, for proper firing of individual ignition modules.
The solid state sensors (crankshaft and camshaft) often provide signals to a control module that provides control for the generation of ignition and fuel injection control signals. Ignition and injector control, in fact, is often consolidated into a single engine control module (ECM).
While the consolidation of engine control functions into a small number of control modules has improved engine performance and reduced pollution, malfunctions have become harder to detect. Often a position sensor receives signals from a number of actuators distributed around a periphery of both the crankshaft and camshaft with the timing of ignition and fuel injection signals determined by a relative position of the sequence of detected signals. When an engine will not run (because of sensor failure or otherwise), a technician must, somehow, test for position sensing signals while cranking the engine. However, when an engine is cranked the heavy current required by a starter results in a low voltage condition on the sensors and may increased the difficulty in detecting the presence and timing of such signals, not to mention the deleterious effect of extended cranking.
Failure of an electronic engine component, in fact, often requires the use of data analyzers or other sophisticated trouble-shooting equipment for detecting and correcting problems. Data analyzers or sophisticated trouble-shooting equipment, on the other hand, tends to be expensive and provide limited functionality relative to price. Because of the importance of automobiles and reliable automobile operation, a need exists for a means and apparatus for simulating operation of engine position sensing without the necessity of actual engine operation or expensive, bulky equipment.
Accordingly it is a primary object of this invention to provide an apparatus that may be used as a substitute for an engine rotational position sensing system.
It is a further object of the invention to provide the functionality of module simulation within a portable device that is adapted to a number of vehicles.
It is a further object of the invention to provide an apparatus that may also be used to detect and give visual indication of proper sensor operation.